Fuel components such as benzene, toluene, and methyl tertiary-butyl ether (MTBE) are frequently detected pollutants in groundwater resources. Ex-situ remediation technologies by activated carbon have been used for treatment for many years. However, due to high cost of these technology, more attention has been given to the in-situ remediation methods of contaminated groundwaters using liquid carbon adsorbents. Literature search showed limited studies on using adsorbents in liquid form for the removal of such contaminants. Therefore, this lab-scale study investigates the capacity of using raw biochar-based liquid activated carbon and iron-modified biochar-based liquid activated carbon to remove these pollutants. The adsorption efficiency of the synthesized liquid activated carbon and iron-modified liquid activated carbon mixed with sand, limestone, and 1:1 mixture of sand/limestone, was tested using batch suspension experiments. Adsorption by granular activated carbon was also investigated for comparison with liquid activated carbon. Results of the study revealed that mixing of liquid activated carbon or LAC-Fe on subsurface materials had not improved the removal efficiency of MTBE. At the same time, it showed a slight improvement in the adsorption efficiency of benzene and toluene. In all cases, the removal by GAC was higher with around 80% and 90% for MTBE and BT, respectively. Results also showed that benzene and toluene were better removed by liquid activated carbon and iron-modified liquid activated carbon (∼ 40%) than MTBE (∼ 20%). It is also found that water chemistry (i.e., salinity and pH) had insignificant effects on the removal efficiency of pollutants under the study conditions. It can be concluded that more research is needed to improve the capacity of biochar-based liquid-activated carbon in removing MTBE, benzene and toluene compounds that will lead to improve the utilization of liquid activated carbon for the in-situ remediation of contaminated groundwaters.

Fuel compounds (BTEX) and fuel additives (MTBE) are pollutants frequently detected in groundwater resources. They may cause serious environmental and health issues and have to be removed from water before use. Ex-situ technologies such as air stripping, advanced oxidation and column adsoroption have been in use for years with different success rates. Recently, more attention has been given to the in-situ remediation methods using liquid/colloidal carbon adsorbents. However, limited studies were found on the use of these adsorbents for the removal of BTEX and MTBE from contaminated waters.Therefore, this study investigates the capacityof using raw biochar-based liquid activated carbon (LAC) and iron-modified biochar-based liquid activated carbon (LAC-Fe) in removing these pollutants. The LAC and Fe-LAC were coated on different host materials (i.e. sand, limestone, 1:1 mixutre of sand and limestone) and granular activated carbon (GAC) under lab-scale batch suspension-adsorption experiment. Results of the study revealed that coating LAC or LAC-Fe on subsurface materials has marginally improved the removal efficiency of MTBE, benzene and toluene but still below that of GAC which reached a removal of 80% for MTBE and more than 90% for BTEX. Results also showed that benzene and toluene were better removed by LAC and LAC-Fe (∼40%) than MTBE (∼20%). There were marginal effects of water chemistry (i.e. salinity and pH) on the removal efficiency of pollutants under the study conditions. The results indicate that more research work is needed to improve the capacity of biochar-based liquidactivated carbonin removing MTBE and BTEX compounds.